He suggested several possible causes for the girlâs death: an illness, an accident inside the van caused by the driverâs behaviour, or a blow to the head.

The Belgian prosecutor has opened an investigation into the death of the child.

Officers found the vehicle contained 26 adults, three children and the body of the girl, named âMawdaâ according to family friends. She was travelling in the back of the van with her Kurdish-Iraqi parents and three-year-old brother, none of whom were injured. A source told the Guardian that police opened fire on the van in an effort to stop it.

The remaining occupants of the vehicle were arrested at the scene. They are being held at a local police station, where they will be questioned.

It is understood that Mawda was conveyed to a local hospital, where she was pronounced dead. Belgian authorities said an autopsy would be carried out on Thursday.

A judicial inquiry has started and statements relating to the incident from the prosecutor in charge of the case and the police are also expected on Thursday. The inquiry will investigate the circumstances surrounding the incident, and seek to establish whether police action was linked to her death.

Sources said Mawda and her family are Kurdish refugees who had recently been deported back to Germany but had made their way back to Belgium, where they stayed until they could afford to make their way to the UK.

They said the girl was travelling with her parents and others in a van being driven by alleged âsmugglersâ to a lorry park in Belgium, where they were to be smuggled on board lorries destined for the UK before the van was intercepted by pol ice.

Police thought the van was behaving suspiciously when it was spotted at about 3am on Thursday morning, on the motorway near the town of Mons, close to the French border. They chased the vehicle, stopping it near the village of MaisiÃ¨res.

Prosecutors are now considering charges, including manslaughter and people trafficking.